Constant velocity coupling and control system therefor

ABSTRACT

A constant velocity coupling  10, 305  which rotabably connects an input shaft  11  to an output shaft  12  by means of a control mechanism or control system  21, 309  which, in particular forms, includes a gimbal arrangement comprised of an inner yoke  22  rotatably connected to an outer yoke  16.    
     The control mechanism including control yoke  21  constrains at least portions of the coupling to lie on or in association with a homokinetic plane  300  of the coupling.  
     In particular forms the control mechanism operates symmetrically about supplementary angle bisector  308.

The present invention relates to couplings between shafts and inparticular forms to universal joints and, more particularly to couplingshaving or seeking to achieve equal instantaneous input shaft and outputshaft angular velocities.

BACKGROUND

The problem of coupling two rotating shafts operating at an angle toeach other has confronted engineers since at least the beginning of theindustrial revolution. The “Cardan Joint” developed initially by Cardanin the 16^(th) century is in principle still in use today despite itsinherent shortcomings and is found for example in virtually every rearwheel drive vehicle.

An inherent flaw in the design of the simple Cardan Joint is the factthat at any angle between input and output shafts other than 180degrees, the angular velocity of the output shaft fluctuatessinusoidally relative to that of the input shaft.

Commonly, and as employed again for example in the drive lines of rearwheel drive vehicles, two Cardan Joints are employed, coupling the inputand output shafts to an intermediate shaft. By maintaining a parallelalignment between input and output shafts and matching orientations ofjoint elements, equal angular velocities can be maintained for the inputand output shafts with the fluctuations now restricted to theintermediate shaft.

However fluctuating stresses arising from the variations in input andoutput shaft angular velocities with that of the intermediate shaft arerequired to be absorbed in the two Cardan Joints. As well it isimpossible in many applications and in particular in road vehicles tomaintain a strict geometric relationship between input and output shaftsgiving rise to vibrations, mechanical stresses and power transmissionlosses.

A partial solution to the problem of maintaining input and output shaftalignment was developed as the so-called “Double Cardan Joint”, oftenreferred to as a Constant Velocity Joint, which is an assembly of twoCardan joints coupled to a short intermediate shaft together with acentering mechanism which constrains both joints to be held in a fixedgeometric relationship to each other such that the input and outputshafts form equal angles with the intermediate shaft. The majorshortcomings of this arrangement reside in the transfer of any axial andradial loads to the centering mechanism resulting in accelerated wearand frictional losses.

Numerous other couplings have been developed to seek to achieve constantangular velocity transfer between shafts. Generally all suffer frombeing approximate solutions to the strict geometrical constraints of atrue constant velocity coupling or achieve an approximation to thegeometry at the cost of high wear frictional losses from slidingcomponents.

It is an object of the present invention to address or ameliorate atleast one of the above disadvantages or at least provide a usefulalternative.

BRIEF DESCRIPTION OF INVENTION

Accordingly, in one broad form of the invention there is provided aconstant velocity coupling wherein the conditions for equalinstantaneous transfer of angular velocities between an input and anoutput shaft are maintained by a control mechanism, said couplingincluding,

-   -   (a) an input shaft rotation axis    -   (b) an output shaft rotation axis    -   (c) a control mechanism,        said control mechanism adapted to constrain at least portions of        said coupling so as to achieve a constant velocity        characteristic.

In a further broad form of the invention there is provided a constantvelocity coupling wherein the angle between an input shaft and an outputshaft is controlled so as to vary the volumetric characteristics of aswash plate hydraulic displacement device.

In yet a further broad form of the invention there is provided a doubleconstant velocity coupling wherein the conditions for equalinstantaneous transfer of angular velocities between an input and anoutput axis are maintained by a control mechanism, said couplingcomprising,

-   -   (a) an input axis    -   (b) an output axis    -   (c) input end yoke    -   (d) output end yoke    -   (e) a control mechanism.

In yet a further broad form of the invention there is provided aconstant velocity joint having an input shaft rotatably connected to anoutput shaft by way of a gimbal mechanism; said joint includingmechanical control means which constrains said gimbal with respect tosaid input axis and said output axis whereby, in use, a constantvelocity characteristic is maintained over a predetermined range ofangles between said input shaft and said output shaft.

In yet a further broad form of the invention there is provided aconstant velocity joint incorporating a control. mechanism based onspherical geometry with respect to a geometric centre defined as theintersection of said input axis and said output axis.

In yet a further broad form of the invention there is provided centeringmeans for a constant velocity joint; said centering means incorporatingjoints defined with respect to spherical triangle structures so as toconstrain at least portions of said joint on a homokinetic plane definedwith respect to the point of intersection of said input axis with saidoutput axis.

In yet a further broad form of the invention there is provided a methodof constraining a first input shaft with respect to a second outputshaft of a constant velocity joint so as to achieve substantiallyconstant velocity behaviour; said method comprising utilising controlmeans centered on and pivotable about one or more axes passing through acoupling centre defined as the intersection of an input shaft with anoutput shaft axis.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described withreference to the accompanying drawings wherein:

FIG. 1 is a perspective view of a fully assembled constant velocitycoupling according to a first preferred embodiment with input and outputshafts in line,

FIG. 2 is a perspective view of the coupling of FIG. 1 with input andoutput shafts at an angular displacement,

FIG. 3 is a perspective view of the coupling of FIG. 1 with somecomponents removed for clarity,

FIG. 4 is a perspective view of the coupling of FIG. 2 illustrating theprinciple of the control mechanism,

FIG. 5 is a perspective view of the complete control mechanism of thecoupling of FIG. 1,

FIG. 6 is an orthogonal view of a control mechanism according to asecond preferred embodiment,

FIG. 7 is an orthogonal view of a linkage mechanism according to a thirdpreferred embodiment,

FIG. 8 is a perspective view of an assembled constant velocity couplingaccording to a fourth preferred embodiment,

FIG. 9 is a perspective view of the coupling of FIG. 8 with the centertube removed,

FIG. 10 is a perspective view of the components of the coupling of FIG.9,

FIG. 11 is a perspective view of a coupling arrangement which canfunction as a hydraulic motor in accordance with a fifth embodiment,

FIG. 12 is a side view of the coupling of FIG. 11,

FIG. 13 is a perspective view of the primary components making up thecoupling of FIG. 11,

FIGS. 14.1 to 14.20 comprise various views of sixth to tenthembodiments,

FIGS. 15.1 to 15.4 comprise various views of an eleventh embodiment,

FIGS. 16.1 to 16.14 comprise various views of a twelfth to fifteenthembodiment,

FIGS. 17.1 to 17.9 comprise views of a sixteenth embodiment,

FIGS. 18.1 to 18.13 comprise views of a seventeenth embodiment,

FIG. 19.1 comprises a perspective view of an eighteenth embodiment,

FIGS. 20.1 to 20.9 comprise views of a nineteenth embodiment,

FIGS. 21.1 to 21.5 comprise views of a twentieth embodiment,

FIGS. 22.1 to 22.7 comprise views of a twenty-first embodiment, and FIG.23 is a graphical depiction of the homokinetic plane and related axessupporting a general discussion of some of the common features of manyof the above referenced embodiments.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A significant number of varied embodiments will now be described.Broadly various ones of the embodiments relate to systems having aninput shaft connected mechanically to an output shaft in such a way thattorque can be transmitted from the input shaft to the output shaftwhilst maintaining a substantially “constant velocity” characteristic.In particular forms the constant velocity characteristic is sought to bemaintained despite variations in angle between the input and outputshaft.

In this specification a “constant velocity” characteristic refers to acharacteristic wherein the instantaneous angular velocity of the inputshaft is matched to the instantaneous angular velocity of the outputshaft throughout a full rotation of the shafts. It is to be understoodthat the constant velocity characteristic is a design goal and variousembodiments may achieve this characteristic to a greater or lesserdegree based on parameters which can include mechanical and structuralvariations in the assembly.

Where variation is allowed in the angle between the input and outputshafts such joints are termed universal constant velocity joints in thisspecification.

Broadly, the constant velocity characteristic as between the input andoutput shafts is achieved by use of a control system which, in theembodiments in this specification, is implemented in mechanical form andis variously termed in various embodiments as a control yoke, a controlmechanism, a linkage mechanism, constraining means, an interposingconnecting member, a centering mechanism and centering means.

Throughout the embodiments the point of intersection of the axes of theinput and output shafts is termed the coupling centre or the geometriccentre and, in some instances, is referred to as the “contact points” ofthe axes of the two shafts.

The coupling centre or geometric centre has significance in that in asignificant number of embodiments this point becomes a common point 6fthe constant velocity joint through which the rotational axes of allpivots forming part of the control system pass (as well as the axes ofthe input and output shafts by definition).

Also, in a significant number of embodiments, a gimbal mechanism can beidentified forming part of the coupling and more particularly includingportions which are controlled by the control system so as to bring outthe constant velocity characteristic. In this specification a gimbalmost commonly comprises an inner substantially circular yoke residingwithin and pivotable with respect to an outer also substantiallycircular yoke. The yokes of the gimbal mechanism are, in turn, pivotablyconnected to respective input and output shafts. The gimbal is at leastpartially constrained in its movements by the control mechanism, mostoften in the form of a control yoke and associated control components soas to impose the constant velocity characteristic upon the relativemovements of the input and output shafts.

The constraining behaviour required to impart the constant velocitycharacteristic is described in the majority of embodiments with respectto the coupling centre or geometric centre as well as the “homokineticplane” of the coupling.

With reference to FIG. 23 the homokinetic plane in this specification isthat plane 300 which lies on the bisector 301 of the angle 302 betweenthe input axis 303 and the output axis 304 of an indicative constantvelocity coupling 305. More specifically the homokinetic plane 300 isdefined to lie at right angles to the plane defined by the input andoutput axes 303, 304. In the particular case of FIG. 23 if it is takenthat the input axis 303 and output axis 304 lie in the plane of the pagethen the homokinetic plane 300 will lie at right angles to the page.

In specific forms the control system is better defined by reference tosupplementary angle 306 which is defined as the angle between, in thisinstance, the output axis 304 and the extension of the input axis 303through the coupling or geometric centre 307. Mathematically thesupplementary angle 306 is 180° minus the angle 302 between the inputand output shafts.

The supplementary angle bisector 308 is the bisector of supplementaryangle 306 and passes through centre 307 and, by definition, lies atright angles to the homokinetic plane 300 and at right angles tobisector 301. The supplementary angle bisector 308 is labelled CC inFIG. 23 and corresponds to axis C in FIG. 4 described with reference tothe first embodiment.

It is a particular characteristic of many of the embodiments of thepresent invention that the control system in the form of the controlmechanism is centred upon axis 308 and operates symmetrically about thisaxis in all modes of operation. In particular embodiments the terms“spherical triangles” and “spherical geometry” are utilised in thecontext of linkages and axes for the control system 309 all of whichrotate about axes which pass through centre 307.

In particular forms the entire control system providing the constantvelocity characteristic (or an arbitrary approximation thereto) can beimplemented using joints which are revolutes about these axes such as,for example, ball or roller bearings, which is to say utilising bearingsurfaces which require no load bearing sliding surfaces.

1. First Embodiment

A first preferred embodiment of a constant velocity coupling will now bedescribed with reference to FIGS. 1 to 5.

With reference to FIGS. 1 and 2 there is shown a constant velocitycoupling 10 in which an input shaft 11 is coupled to an output shaft 12.Input shaft 11 is rigidly connected to input shaft boss 13. Output shaft12 is rigidly connected to output shaft yoke 14 which is provided withjournals 15.

Output shaft yoke 14 is pivotally connected to outer yoke 16 by pivotshafts 17 and bearings (not visible) in outer yoke journals 18.

Input shaft boss 13 is able to pivot about shaft 19 located throughinner yoke journals 20.

A control yoke 21 is pivotally connected to outer yoke 16 and inner yoke22 by means of shafts 23 in control yoke journals 24 and bearings (notvisible) in outer yoke journals 25 and inner yoke journals 26. The axisY-Y defined by control yoke 21 and the journals of outer yoke 16 andinner yoke 22 is the principle axis of the coupling 10.

As shown in FIGS. 1 and 2, all pivotal axes, together with input shaftaxis 27 and output shaft axis 28 intersect at the coupling center 29.

With reference to FIG. 3 inner yoke 22 and outer yoke 16 have beenremoved for clarity to show first scissor mechanism 30 comprising firstscissor arm 31 and first scissor links 32 and 33. Also visible in FIG. 3is input shaft extension 34 and input shaft control pin 35. The axis ofinput shaft control pin 35 intersects coupling center 29 and lies in theplane defined by input shaft axis 27 and input shaft boss axis 36.

With reference to FIG. 4 where input shaft 11 has been removed forclarity, the geometric characteristics of a first half of scissorcontrol mechanism 30 will now be explained.

Output shaft yoke 14 is provided with output shaft control pin 37. Theaxis A of control pin 37 lies in the plane defined by output shaft axis28 and the axis X-X through the centers of output shaft yoke journals15, and intersects coupling center 29.

Control yoke pivot pin 38 is rigidly connected at the center of controlyoke 21 such that its axis C intersects coupling center 29. Firstscissor arm 31 pivots about control yoke pivot pin 38 and is provide atits outer ends with pivot shafts 39, the axes of which also intersect atcoupling center 29. First scissor links 32 and 33 are pivotallyconnected to pivot shafts 39 of first scissor arm 31. The outer end offirst scissor link 32 is pivotally connected to input shaft control pin35 (refer to FIG. 3) and outer end of first scissor link 33 is pivotallyconnected to output shaft control pin 37.

Because all axes of rotation of first scissor mechanism 30 intersect atcoupling center 29, it is clear that a rotational displacement of inputshaft control pin 35 out of the plane defined by output shaft axis 28and the axis X-X will cause a rotation of control yoke 21 about axisX-X. If the inter-center distances of pivot shafts 39 from control yokepivot pin 38 and pivot centers of links 32 and 33 are equal, it followthat angular displacement of control yoke 21 will be half that of theangular displacement of input shaft control pin 35.

This angular ratio holds true as long as axes A, B and C are constrainedto lie in a common plane passing through coupling center 29. As shown inFIG. 5, the control scissor mechanism actually comprises dualsymmetrical scissor arms and linkages which ensure that this conditionis met. The mechanism can be considered to lie on a series of concentricspheres such that the nominal pivot intersection points of scissor armsand linkages lie at the vertices of spherical triangles, so constrainedthat corresponding angles within the triangles remain equal as thescissor mechanism re-orients due to the inputs from the two controlpins.

For clarity the following example refers only to one half of the dualscissor control mechanism but it will be understood that the motionsdescribed are controlled by the complete mechanism.

With reference to FIGS. 3 and 4, let it be assumed that the axis 28 ofoutput shaft 12 is retained in the orientation shown, that is lying in ahorizontal plane through X-X. If now input shaft 11 is rotated downward,only about axis X-X, that is the axis 27 of input shaft 11 continues tolie in the same vertical plane as that passing through the axis ofoutput shaft 12 and axis Y-Y, then the end of axis B at its pivotalconnection to first scissor link 32, will follow a path upward on asphere radius B centered at coupling center 29. That path is a smallcircle on the sphere radius B and lies in a vertical plane parallel tothe vertical plane through the axes of input shaft 11 and output shaft12. This displacement of link 32 forces primary scissor arm 31 to rotateabout control yoke pivot pin 38 fixed to control yoke 21. But scissorarm 31 is constrained by its connection to link 33 and output shaftcontrol pin 37. If the angle between the plane defined by axis X-X androtated axis B and the horizontal plane through X-X is ax, then thescissor arm 31 and linkages 32 and 33 will rotate axis C into a planethrough X-X at angle a/2. Now the angle between input shaft axis 27 andthe horizontal plane is also a, so that it follows that the axis Y-Ybisects the angle (180−α) between input shaft axis 27 and output shaftaxis 28.

Clearly the axis Y-Y now lies in the plane bisecting the obtuse anglebetween input shaft axis 27 and output shaft axis 28 and normal to theplane defined by axes 27 and 28. This plane is the so-calledhomo-kinetic plane and axes Y-Y may be defined as the axis of symmetryof the coupling.

It can be shown that the axis Y-Y satisfies this relationship to theaxes 27 and 28, that is it lies in the homo-kinetic plane, for anyrelative angle between input shaft 11 and output shaft 12, within thephysical constraints of the coupling 10.

This satisfies the theoretical condition for a constant velocitycoupling which requires that the input and output shaft axes meet at apoint and that the contact points between the two shafts lie on the axisof symmetry in the homo-kinetic plane.

Clearly all relative movements of components within the coupling arerotational and are realized by roller bearings, thus largely eliminatingtorque losses through friction;

2. Second Embodiment

In a second preferred embodiment, the scissor control mechanismpreviously described may be interchanged for a geared mechanism 40 asshown in FIG. 6.

With reference to FIGS. 3, 4 and 6 the center 45 of main arm 41 andcentral gear. 44 are mounted so as to rotate about control yoke pivotpin 38. Linkage arms 42 and 43 are provided with meshing gear segments48 and 49 respectively and at their outer ends with pivot centres 46 and47. Linkage arms 42 and 43 are pivotally mounted to main arm 41 onshafts 50 and 51.

All rotation and pivot axis of control mechanism 40 are radial to thegeometric center 29 of the coupling 10 (see FIG. 4). Linkage arms 42 and43 are of equal length and subtend equal angles with main arm 41. Thusthe pivot centers 46 and 47 and the center of central gear 44 areconstrained to lie on a great circle arc of a sphere centered on thegeometric center 29, and the center of gear 44 will always lie at themidpoint of that great circle arc regardless of any variation in thelength of that arc.

On assembly, pivot 46 of control mechanism 40 is connected to inputshaft control pin 35 and pivot 47 is connected to output shaft controlpin 37.

It will be seen that any change in the angle between input shaft 11 andoutput shaft 12 will cause displacements of linkage arms 42 and 43. Forexample, let it be assumed that pivot center 47 of linkage arm 43remains stationary. Then any displacement induced in pivot center 46 byinput shaft control pin 35 will induce half that displacement in thecenter of gear 44. Thus the axis through control yoke pivot pin 38 willcontinually bisect the complementary angle between input shaft 11 andoutput shaft 12 and remain in the plane defined by the axes of theshafts 11 and 12. It follows then that the axis Y-Y will be constrainedto lie in the homokinetic plane as previously defined.

3. Third Embodiment

In a third preferred embodiment with reference to FIG. 7 there isprovided a linkage system 60 which takes the place of inner yoke 26 andouter yoke 27 of coupling 10 in FIGS. 1 and 2. Shaft 61 is rigidlyconnected at its outer ends to linkage members 62 and 63 each of whichhas at its outer end boss 64 and 65 respectively. Boss 64 and boss 65carry control trunnion shafts 66 and 67 respectively. Linkage system 60is further provided with linkage arms 68 and 69 each provided with ends70 and 71 pivotally connected to control trunnion shafts 66 and 67respectively. Linkage arms 68 and 69 have outer ends 70 and providedwith output shaft yoke trunnion shafts 74 and 75.

Linkage members 62 and 63 and linkage arms 6B and 69 lie withinspherical shells centered on the intersection point 80 of the axis ofshaft 61 and axis Y-Y and all rotation axes of the linkage system 60intersect at axes intersection point 80.

On assembly axes intersection point 80 is coincident with the geometriccenter 29 of the coupling 10 of FIG. 1.

In this embodiment input shaft boss 13 of input shaft 11 of FIG. 1,rotates about shaft 61 of the linkage system 60 shown in FIG. 7, andoutput shaft yoke journals 15 of output shaft yoke 14 are connected totrunnion shafts 74 and 75. Control yoke journals 24 of control yoke 21are connected to control trunnion shafts 74 and 75.

As before, the control yoke axis Y-Y is constrained to remain in thehomokinetic plane by the use of either the scissor control mechanism orthe geared control mechanism described above.

An advantage of the arrangement of axis Y-Y and shaft 61 at a preferredangle of 45 degrees in this embodiment is that the space so createdallows greater freedom of movement of the various rotational elementsand the control mechanisms described above.

4. Fourth Embodiment

In a fourth preferred embodiment illustrated in FIG. 7, there isprovided a double constant velocity coupling 100 comprising input shaft111 and output shaft 112. Each of shafts 111 and 112 is provided withyokes 113 and 114 respectively in which the shafts 111 and 112 arepivotally connected about axes X-X and X′-X′. Yokes 113 and 114 are inturn pivotally connected to connecting tube 115, each yoke 113 and 114able to rotate about axes Y-Y and Y′-Y′ respectively.

As shown in FIGS. 8 and 9, input shaft 111 and output shaft 112 are ofidentical construction each being provided with shaft extensions 116 and117 respectively with each shaft extension having control pins 118 and119 respectively. The axes of control pins 118 and 119 each lie in theplane defined by the shaft axis and the shaft rotation axis X-X andX′-X′ of shafts 111 and 112, and intersect with the intersection ofthese axes.

Positioned in the center of connector tube 115 (removed in FIGS. 8 and 9for clarity) is control assembly 120 including upper and lowertransmission blocks 121 and 122 respectively. Blocks 121 and 122 arehinged together about the control block hinge shaft 129 lying on centralaxis Z-Z of connector tube 115. Shaft 129 is supported by means of afixed pivot (removed for clarity) attached to the inner wall ofconnector tube 115.

As shown in FIG. 8 all rotation axes at the input shaft end of thecoupling 100 are radial to the intersection of axes X-X and Y-Y;similarly all rotation axes at the output end of coupling 100 are radialto the intersection of axes X′-X′ and Y′-Y′.

Any rotation within the physical constraints of the coupling of inputshaft 111 about its axes of rotation X-X and Y-Y will cause controlshaft 118 to displace connected linkages 125 and 126 causing in turn arotation of transmission blocks 121 and 122 about hinge shaft 129.Corresponding linkages 125 and 126 at the output end of control assembly120 are forced to duplicate the displacement generated at the input end,transferring the displacement to linked control shaft 119, therebycausing output shaft 112 into corresponding rotations about its axesX′-X′ and Y′/Y′.

The angular displacements of input shaft 111 and 112 are symmetricalabout a plane normal to the plane defined by the axes of shafts 111 and112 and passing through the center of control assembly 120. As such theplane lies on the intersection of the axes of shafts 111 and 112,bisecting the angle between them and containing the axis of symmetry.That plane is therefore the homo-kinetic plane and the conditions forconstant velocity of input and output shafts are satisfied.

Again, all relative movements between components of the coupling in thisembodiment are rotational and are realized by roller bearings, largelyeliminating torque losses due to friction.

5. Fifth Embodiment

A fifth preferred embodiment is now described wherein a constantvelocity coupling is provided in which the angle between input andoutput shafts is maintained at some desired value by a variable controlmechanism so as to vary the volumetric displacement of a swash plateoperated hydraulic pump or motor. In this preferred application thereciprocating pump or motor elements are incorporated within thestructure of the coupling.

In this fifth preferred embodiment a constant velocity coupling isadapted to incorporate a variable swash plate hydraulic displacementdevice.

With reference to FIG. 11 there is shown a constant velocity coupling200 with input shaft 211 and output shaft 212. It will be obvious tothose skilled in the art that the terms “input shaft” and “output shaft”in this embodiment can be assigned to each of these elementsinterchangeably depending on the application of the coupling.

The axis of each of shafts 211 and 212 intersect at a point 220coincident with the intersection of axes X-X and Y-Y in FIG. 11; point220 defining the geometric center of the coupling. The angle between theaxes of shafts 111 and 112 may be varied from time to time as desiredwithin the physical constraints of the coupling by a suitable controlmechanism. The control mechanism is further adapted to maintain theangle of control yoke 213 in a fixed relationship to that angle setbetween shafts 211 and 212. This relationship is illustrated in FIG. 12,where if the supplementary angle between shafts 211 and 212 is α, thenthe axis of rotation of control yoke 113 bisects the angle α. Thus theaxis Y-Y is constrained to rotate in the homokinetic plane, satisfyingthe condition for a constant velocity coupling.

FIG. 13 shows the disparate elements of the coupling including controlyoke 213, inner yoke 214 and outer yoke 215. Input shaft 211 is rigidlyconnected to swash plate 216 provided with swash plate trunnion shafts217.

On assembly, swash plate trunnion shafts 217 pivotally connect in inneryoke journals 218 of inner yoke 214. Inner yoke 214 is pivotallyconnected by its inner yoke trunnion shafts 219 to the outer yokejournals 221 of outer yoke 215. In turn outer yoke 215 is pivotallymounted by its outer yoke trunnion shafts 222 in output shaft yokejournals 223 of output shaft yoke 224. Control yoke 213 (shown from itsyoke end) is pivotally connected by control yoke journals 225 to theextended inner yoke trunnion shafts 219 of inner yoke 214.

The output shaft 212 of coupling 200 is further provided with cylinderblock 226. Cylinder block 226 is provided with a radial array ofcylinders 227. Each of cylinders 227 accepts a piston 228 provided atits compression end with seals 229 and at its opposite end with ballsocket 230. Each piston 228 is connected by its ball socket 230 to firstend 231 of connecting rod 232. Second end 233 of connecting rod 232 isconnected to a ball socket 234 of swash plate 216.

On assembly when input shaft 211 and output shaft 212 are coaxially inalignment, the face of swash plate 216 is oriented normal to the axis ofoutput shaft 212 and thus the axes of cylinders 227. In this situationthe rotation of input shaft 211 and output shaft 212 about this commonaxis will leave pistons 228 stationary in cylinders 227. When an angle ais introduced between input shaft 211 and output shaft 212, by means ofthe control mechanism, a reciprocal axial displacement is induced ineach of the cylinders 227 by pistons 228 for every revolution of thecoupling 200.

The volumetric displacements caused by the reciprocal movement ofpistons 228 in cylinders 227 within a revolution of the coupling 200increases as the angle a increases.

Possible advantages of this configuration are:

-   -   A. Previous are used a rzeppa type constant velocity joint with        the inner member of the constant velocity joint held coaxial        with the cylinder body and the outer member of the constant        velocity joint forming th swash plate. With such an arrangement        the entire torque of the assembly was transmitted through the        constant velocity joint and the torque transmission members at a        lesser radius than the swash plate with the result that the        torque transmitting means were subject to high loadings.    -   B. With present configuration torque may be transmitted to or        from the swash plate by one of two methods both of which are        superior to the prior art:        -   1. Torque transmitted by shaft connected to the cylinder            body—In this case the torque transmitting means is at a            greater radius than the swash plate with the result that the            torque transmitting members are subject to lesser torque            loads than with the prior art.        -   2. Torque transmitted by shaft connected to the swash            plate—In this case the torque transmitting members of the            constant velocity joint are not subject to the working            torque of the device, the only load transmitted through the            coupling is the torque necessary to rotate the cylinder            body.

6. Sixth Embodiment

This embodiment referring to FIGS. 14 provides for a joint of themodified Hooke's type where axis A5 continuously lies on the homokineticplane due to the operation of a system of gears and levers arranged insuch a manner that the rate and degree of revolution of a firstactuating gear is at all times identical to the rate and degree ofrevolution of a second actuating gear by means of maintaining the angleof inclination between axis A3 and the axis of a first actuating gearthe same as the angle of inclination between axis A4 and the axis of asecond actuating gear. Alternatively a system of levers alone isenvisaged where the levers perform similar functions to theabovementioned gears.

Several preferred methods of implementing this embodiment will now bedisclosed. In each preferred method there is provided two halves of amodified Hooke's joint as shown in FIG. 6. It will be observed that thejoint shown in FIG. 6 is identical to the joint shown in FIG. 1excepting that the cruciform member 6 as shown in FIG. 1 is omitted anda circular member 7 is located to yoke 4 such that it is free to rotateabout axis A4. The size of ring member 7 and yoke 4 is such that theassembly may fit inside the inside the ring member 5 which is attachedto yoke 3. The components shown in FIG. 14.6 are common to all preferredembodiments of the present invention.

FIG. 14.7 shows a cruciform member with two of the arms having the sameaxis longer than the two other arms such that the two longer arms have acombined length at least equal to the outside diameter of the largerring member 5 and the two shorter arms have a combined length less thanthe internal diameter of ring member 7 such that when assembled thelonger arms connect the two halves of the joint shown in FIG. 14.6 ataxis A5 and the cruciform member is free to rotate on axis A5 withinring member 7.

FIG. 14.8 is the cruciform member shown in FIG. 14.7 with fourintermeshed bevel gears one of which is located on and free to revolveon each of the arms of the said cruciform member. The two gears whichare located on the shorter arms of the cruciform member have a leverrigidly attached to them but not shown in this drawing.

FIG. 14.9 shows one of the gears with the rigidly attached lever arm.The lever arm has a ball 25 the end of it. Within the parametersdiscussed below neither the length of the lever arm nor its offset alongthe axis of the gear is critical. One such gear is located on each ofthe shorter arms of the cruciform member such that a lever arm extendsout on opposite sides of the cruciform member. The lever arm attached toone of the gears must be aligned half a tooth different from thealignment of the other lever arm and gear such that the axis of the twolonger arms of the cruciform member bisects the angle between the twolevers as they rotate in mesh with the other two gears.

FIG. 14.10 shows a yoke with a ball member rigidly attached to thecentre of the inside surface of the yoke, both yokes have such a ballmember attached.

FIG. 14.11 shows a linkage member being a rod with a ball socket ateither end adapted to connect at one end to the ball on the end of thelever shown in FIG. 14.9 and at the other end to the ball in the centreof the yoke member as shown in FIG. 14.10.

The components described above and shown in FIGS. 14.6, 7, 8, 9, 10 and11 are assembled such that the longer arms of the cruciform memberextend through the holes in ring members 5 and 7 such that the said ringmembers are located in respect to one another by the longer arms of thecruciform member and free to rotate about axis A5 and the cruciformmember is also free to rotate on axis A5. The positions of the variouscomponents upon assembly is such that when the axis of shaft 1 and shaft2 are in line the component parts have the relative positions as shownin FIG. 14.12 and in that view axis A3 and A4 and the axis of the gearslocated on the shorter arms of the cruciform member are all coaxial andaxis A5 is perpendicular to the plane of axis A3, A4, A1 and A2.

The joint as represented in FIG. 14.12 is intentionally shown with yoke3 substantially larger then yoke 4 in order to illustrate therelationship between the various components. A linkage member 13 (asshown in FIG. 14.11) is connected at one end to the ball at the end oflever 11 and at the other end to the ball which is fixed to the centreof the inside surface of yoke 3 a similar linkage member 14 is similarlyconnected in the other half of the joint and the length of each linkagemember and the length of the two lever arms 11 and 12 are determined asfollows. The important consideration is that the triangle which isformed between the point of axis of the lever arm 11 and the centre ofthe ball which is fixed to the centre of yoke 3 and the centre of theball at the end of lever 11 has the same internal angles as the trianglesimilarly formed in the other half of the joint; in other words the twotriangles so formed should be identical except for size in thisembodiment.

If the centrelines of the lever arms project to the centre of thecruciform member (or disk member described below) then the internalangles of the triangle remain the same at all times while the jointrotates. However if the centreline of the lever arms project to a pointwhich is offset from the centre of the cruciform member the internalangles of the triangle continuously change with revolution of the joint.If the centreline of the lever arms are offset from the centre of thecruciform member it is essential that both lever arms are offset to theextent that identical triangles are formed on either side of the joint.

It will be seen that with operation of the joint described above both ofthe triangles described above effectively rock about their respectivebases and also rock about the point of axis of the lever arms with theeffect that when axis A3 and A4 are coaxial then the axis of the twolevers are also coaxial with axis. A3 and A4 and whenever axis A3 and A4are not coaxial the axis of the lever arms and associated gears alwaysbisects the angle between axis A3 and A4 as they rotate about axis A5with the result that the angle between the axis of the actuating levers11 and 12 and their associated gears are always equally inclined to axisA3 and A4 respectively with the result that with rotation of yoke 3about axis A3 and with rotation of yoke 4 about axis A4 the levers 11and 12 and their attached gears will contra rotate about their axes atdifferent rates and to a different degree than the rotation of the yokesabout axis A3 and A4. However the said levers and associated gears willcontra-rotate at equal rates and to equal degree as one another with theresult that axis AS will continuously lie on the homokinetic plane andthe joint will operate as a constant velocity joint in that the angularvelocity of shaft 1 and shaft 2 will always be equal no matter what theangle of inclination of the said shafts to one another and will do soeven if the angle of inclination alters during operation.

7. Seventh Embodiment

In another embodiment the cruciform member of FIGS. 14 and four bevelgears and associated levers are replaced with a member adapted to holdtwo meshing gears in such a position that when the axis of shaft 1 andshaft 2 are in line their respective axis are perpendicular to the axesof both of the gears and axis A5 is perpendicular to and central to theplane between the axis of the two gears. A lever arm is rigidly affixedto each gear and a ball is on the end of each lever arm. With referenceto FIG. 14.13 the member adapted to hold the two gears is a disk likemember the diameter of which will fit inside ring 7. The disk member hastwo lugs which are used to locate and provide the axis for rings 5 and7. The disk member has a rectangular hole through it so as to permit themeshing of the two gears through the disk. The disk member is free torotate on axis A5. The disk member has two protrusions from each faceand the axle for each of the gears is held by these protrusions. FIG.14.14 is a side elevation of the disk member with the two gears inplace. The lever arms one of which is rigidly attached to each gear arepart shown. The operation of this disk like member and associated gearsand levers is identical to the operation detailed above in respect tothe cruciform member and four bevel gears and the same considerationsapply.

8. Eighth Embodiment

Another embodiment illustrated in FIGS. 14 is a system of leversarranged to pivot on each of the four arms of the cruciform memberdescribed above where their action is similar to the arrangement of thefour intermeshing gears.

9. Ninth Embodiment

Another embodiment illustrated in FIGS. 14 which may be used with eitherthe cruciform member and the four bevel gears or the disk like memberand the two gears or the system of levers alone is as follows. The ballmember which is attached to the centre of the inner surface of each yokeis omitted and each of the yolks has an arcuate groove formed in theinside face of the yolk such that upon assembly the ball at the end ofthe lever arms is located in that groove so that with operation of thejoint and as axis A3 and A4 change angle between each other the ball oneach lever is caused to traverse the groove. If constructed in thismanner the triangle referred to above is not available to maintain thecorrect relationship between the axis of the actuating gears and axis A3and A4 so a different means of maintaining equal inclination between theaxis of the gears and levers and the axis of their respective actuatingyokes must be employed. One such method is to employ the scissor actionof rings 5 and 7 which occurs as the angle between axis A3 and A4changes.

One method of employing this scissor action is to rigidly fix a rod toeither one of the longer arms of the cruciform member or one of the lugsof the disk like member as the case may be such that it is orientedperpendicular to the plane of the four arms of the cruciform member orthe face of the disk like member as the case may be, two lever arm areused one of which is rotatably fixed to each of the ring members 5 and 7at one end and the other end is fixed to a member which joins both leverarms at their other end by a member which slides along the rod which isfixed to the arm of the cruciform member or disk member as the case maybe so that the rod continuously bisects the angle between ring members 5and 7. FIG. 14.15 is a representation of just such a scissor mechanism.

It will also be appreciated that without departing from the presentinvention various other configurations of gears and levers will alsowork to maintain the relationship between the various components asdisclosed herein.

It will also be appreciated that without departing from the presentinvention it is also possible to arrange a system of levers aloneinstead of the gear and lever systems to maintain the relationshipsdescribed herein.

It has been found that in respect of the sixth to ninth embodiments itis helpful to provide separate means to ensure that the shorter arms ofthe cruciform member bisect the angle between axis A3 and A4 wheneverthey are not coaxial and in the seventh embodiment it is also helpful toprovide separate means to ensure that the plane of the member shown inFIG. 14.13 bisects the angle between axis A3 and A4 whenever they arenot coaxial. In both instances such centering means may be to utilisethe scissor action between member 5 and 7 as discussed above in respectto the eighth embodiment.

10. Tenth Embodiment

There is now disclosed with further reference to FIGS. 14 a further,unique and novel means of providing a constraining means so as tofacilitate a constant velocity joint by constraining axis AS on thehomokinetic plane.

This further novel means provides for members which describe twoidentical spherical triangles one in each half of the joint describedbelow.

As with the previously disclosed constant velocity universal joints themembers shown in FIG. 6 are used however in this novel embodiment andwith reference to FIG. 14.16 a disk like member 15 is provided. The diskmember has two pins or trunnions 16 which provide the connecting meansbetween ring members 5 and 7 and forms axis A5. The disk like member hasa hole 17 through the center of the disk. It will be seen that uponassembly of the two halves of a joint as shown in FIG. 14.6 using thedisk like member shown in FIG. 14.16 then all of axis A1, A2, A3, A4 andA5 intersect at a point. For the purpose of the present disclosure thepoint at which all of the said axes intersect will be called “thegeometric centre”.

With reference to FIG. 14.17 there is also provided a double ended cranklike member having a crank pin 18 at each end where the crank pin isangled such that upon assembly the axis A6 of each of the crank pins areeach on a radius which intersects the geometric centre.

Upon assembly and with reference to FIG. 14.18 the shaft of the cranklike member is passed though the hole in the disk like member shown inFIG. 14.16 such that one crank pin is on either side of the said disklike member.

With reference to FIG. 14.19 which shows the two yokes of a joint a pin19 is fixed to the inside arc or surface of the yoke members 3 and afurther pin 20 is similarly fixed to the inside surface or arc of yoke 4such that the axis of each of the said pins also lies on a radius whichintersects the geometric centre. The pins are situated such that theyare on the same side of the joint as one another rather than diagonallyopposite.

With reference to FIG. 14.20 a further member 21 is provided having ahole 22 at one end such that member 21 can be located on pin 19 and afurther hole 23 such that the other end of member 21 may be located onthe first pin 18, a further similar ember is provided and is located onone end on pin 20 and at the other on the second pin 18. The length ormore correctly the angle between the holes at either end of member 21 isas set out below.

Upon assembly of the joint and when the joint is in a position whereaxis A1 and A2 are in line and axis A3 and A4 are coaxial the axis ofthe crank pins 18 is on the plane of axis A5 and A1 and A2 and the axisof pins 19 and 20 are each on the plane of axis A3 and A4 and A1 and A2.The angle between the holes in either end of member 21 is such that therelationships described in this paragraph are held or true.

With the novel restraining means last described herein it will be seenthat a spherical triangle is described by the great circle arcs betweenfirstly the axis of pin 19 and axis A1, secondly Axis. A1 and the axisof the first crank pin, thirdly the axis of the first crank pin and theaxis of pin 19. A similar spherical triangle is described between thecorresponding components on the other side of the joint. It will be seenthat with rotation of the assembled joint at any time when shafts 1 and2 are inclined to each other a unique spherical triangle is formed ateach point of revolution and angle of inclination and such a triangle isformed on each half of the joint with the result that the axis of thecrank like member is equally inclined to firstly axis A1 and secondlyaxis A2 with the result that the plane of the disk like member 15 andtherefore axis A5 is constrained to remain continuously on thehomokinetic plane of the joint.

11. Eleventh Embodiment

The present embodiment of FIGS. 15 provides firstly a linkage mechanismas set out in FIG. 15.1 hereof and described below and secondly asdescribed below a constant velocity universal joint utilizing the saidlinkage mechanism.

With reference to FIG. 15.1 hereof the linkage mechanism disclosedconsists of the following. Members 1 and 2 which are two similar memberseach having a hole formed in each end with the axis of the said holesintersecting at a point. Members 3 and 4 are also two similar membersand also similar to members 1 and two excepting that members 3 and 4have the holes formed in each end at a greater radius than do members 1and 2. Members 1 and 2 are connected to one another by a shaft 5.Locating pin 6 connects members 1 and 3 such that members 1 and 3 mayrotate in relation to one another about axis A1. The said members areassembled in such a manner that the normal axis of shaft 5 intersectsaxis A1. It will be seen that with such an assembly members 1 and 2which are connected together by shaft 5 will rotate in unison about axisA1 such that the normal axis of shaft 5 rotates about axis A1 andsimilarly if members 3 and 4 are held in fixed relationship to eachother then they also will rotate in unison about axis A1 such that theiraxis, axis A2 will also rotate about axis A1 and axis A1, A2 and thenormal axis of shaft 5 will always intersect at the geometric centre ofthe above described linkage mechanism.

One application utilizing the above described linkage mechanism is aconstant velocity universal joint as now disclosed. FIG. 15.2 depicts ashaft with a hole formed in one end such that shaft 5 may be passedthrough the said hole. FIG. 15.3 depicts a yoke as commonly used inuniversal joints such as the common hooke's joint (also known as acardan joint). Holes 13 and 14 are formed in the arms of the yoke suchthat the yoke may be located in relation to the linkage mechanismdescribed above by locating pins 8 and 9 in holes 13 and 14respectively. Shaft 10 is located on shaft 5 such that axis A3 being thenormal axis of shaft 10 intersects axis A1 and A2 at the geometriccentre of the linkage mechanism. Similarly it will observed that uponassembly as disclosed above axis A4 which is the normal axis of the yokemember 12 also intersects Axis A1 and A2 at the geometric centre of thelinkage mechanism. It will be seen that with such an assembly at anytime where axis A3 and A4 are not in line or coaxial to one anotherrotation of shaft 10 and yoke 12 about axis A3 and A4 respectively willresult in members 1 and 2 rotating in unison about axis A1 whileconcurrently members 3 and 4 will also rotate in unison about axis Albut in opposite direction of rotation to members 1 and 2. With such anassembly it will be observed that whenever axis A3 and A4 are not inline or coaxial and axis A2 and the normal axis of shaft 5 are not inline or coaxial then the plane of rotation of axis A1 always bisects theangle between the plane of rotation of axis A2 and the normal axis ofshaft 5 and additionally the plane of rotation of axis A1 isperpendicular to the plane between axis A3 and A4 and hence therequirements of a constant velocity joint are present at all times.

FIG. 15.4 is a representation of the linkage mechanism assembled withshaft 10 and yoke 12 so as to form a constant velocity joint asdescribed above. In this representation axis A3 and A4 are inline andaxis A2 and the normal axis of shaft 5 are also in line or coaxial. Inthis representation axis A2 and the normal axis of shaft 5 are on theplane of the paper while axis A1 enters the page from the bottom at aninclination equal to the angle between the holes in members 1,2,3 and 4.In this particular representation it will be seen that if shaft 10 wasrotated anticlockwise on the plane of the paper and yoke 12 was rotatedclockwise on the plane of the paper then shaft 5 would rotate about axisA1 and Axis A2 would also rotate about axis A1 but on the oppositedirection.

There is herein disclosed a linkage mechanism having three intersectingaxes two of which rotate in relation to the third. There is alsodisclosed a constant velocity universal joint utilizing the said linkagemechanism and is a constant velocity universal joint having at leastthree axes two of which rotate about the third. This embodiment shouldutilise the same control system including the control yoke and controlpins of the first embodiment, so as to constrain axis A1 on thehomokinetic plane,

12. Twelfth Embodiment

The term “spherical geometry” as intended for the purpose of thisembodiment is as follows and with reference to FIGS. 16. FIG. 16.1 is adepiction of a sphere with a spherical triangle and associated trihedralset out on it. With reference to FIG. 16.1 axis 2 and 3 are diameters ofsphere 1. Spherical triangle sides AD, AO and AZ are the interceptedgreat circle arcs of trihedral face angles D, Z and 0 respectively andangles A,B and C are the internal angles of the spherical triangle AD,A0, AZ. With further reference to FIG. 16.1 it will be seen that ifspherical triangle AD, A0, AZ is rotated about either radius 4 or radius5 or diameter 3 then the rotating radii describe cones within thesphere. With further reference to FIG. 1 it will also be seen that ifany of the face angles D, 0 or Z are changed then its intercepted greatcircle arc also changes as does the spherical triangle AD, A0, AZ.Obviously all of the rules of spherical geometry apply.

With reference to the above the term “spherical geometry” for thepurpose of this embodiment means the movement of component parts of ajoint in such a manner that they describe or form spherical geometricforms or functions.

The primary purpose of the present embodiment is to provide firstly abasis for a genre of constant velocity universal joint having membersinterposed between a first rotating shaft and a second rotating shaftwhere each of the moving or operating interposed members describespherical geometric forms or functions and the second purpose of thepresent invention is to provide several specific and novel iterations ofconstant velocity universal joint based upon spherical geometry.

From the following it will be seen that basing constant velocity jointson spherical geometry 15 rather than geometry other than sphericalprovides for joints of reduced size and also joints having no slidingand/or skidding components.

The sixth embodiment described earlier provided for a means to formidentical spherical triangles in each half of a joint so as to provide ameans to maintain an interposed member on the homokinetic plane of thejoint described therein. The above mentioned embodiment described acentering means consisting of a shaft having a crankpin at either endand also provided for two yokes each having a pin located on the insidesurface and where the extended axis of the said crankpins and of thesaid pins intercepted the geometric centre of the joint described. Forthe purpose of clarity the joint described in the sixth embodimentcomprised of a modified Hooke's joint having two halves as depicted inFIG. 16.2 herewith. An interposed connecting member is depicted in FIG.16.3 and consists of a disk like member 15 with a hole 17 in the centerand two lugs 16 fixed to it such that the two lugs are used to connectthe two halves of the joint shown in FIG. 16.2 by locating the said lugsin the holes 8, 9, 10 and 11 shown in FIG. 16.2. FIG. 16.5 depicts ashaft member 12 having arms 13 and crankpins 18 located at either endoriented in such a manner as the extended axis A6 of the said crankpinsintersect at the geometric centre of the joint when assembled. FIG. 16.4shows a depiction of shaft 12 assembled with disk like member 15. FIG.16.6 shows yoke member 3 and yoke member 4 each of which has a pin 19and 20 protruding from the inside surface of the yokes and which pinsare oriented such that the extended axis of each pin intersects thegeometric centre of the joint upon assembly. The said yokes areassembled such that the pins 19 and 20 are on the same side of the jointor in other words that the extended axis of pins 19 and 20 are not inline or coaxial. Two instances of a further member 21 as depicted inFIG. 16.7 are provided, this member has a hole 22 at either end and thelength of the said member and the angle between the said holes is suchthat upon assembly of the joint the first such member is located at oneend on pin 19 and on the other on its adjacent pin 18 and the secondsuch member is located on pin 20 and the second pin 18. The length ofeach of the members 21 and the angle between the holes 22 in each ofmember 21 is such that upon assembly of the joint and when the axis A1and A2 are in line two identical right spherical triangles having thesides G,H,I and J, K, Las depicted in FIG. 16.8 are formed one in eachhalf of the joint and with the right angle being on the axis of theinput or output shaft as the case may be. The first member 21 forms sideI on the first right spherical triangle and the second member 21 formsside J on the second right spherical triangle.

FIGS. 16.8A and 16.8B are both depictions of the joint according to theabove described embodiment. It will be observed by an analysis of FIGS.16.8A and 16.8B together with the foregoing that at any time when theaxis of the input shaft and the output shafts are inclined to oneanother a unique spherical triangle is formed for each possiblerotational position and angular position and it will be further observedthat the spherical triangle formed in each half of the joint by virtueof the construction must be identical to each other with the result thatthe plane of rotation of axis A5 as shown in FIG. 16.1 and as located bylugs 16 must always bisect the angle which exists from time to timebetween the axis of the input and output shafts.

While the joint and centering means described above utilizes sphericalgeometry to provide the centering means the remaining components otherthan the centering means all describe disks or planes centred upon thegeometric centre of the joint upon rotation and each of these disks maybe described by simple planar geometry. From the following it will beseen that it is advantageous to modify the above described jointaccording to the present invention which is to provide construction suchthat the components and the relationship between components describeshapes and forms found in spherical geometry and not in planar geometry.

13. Thirteenth Embodiment

With reference to FIG. 16.9 of FIGS. 16 there is provided a member 22which is a disk-like member with a hole 32 in the centre. Its purposeand function is identical to member 15 as described above in respect ofthe twelfth embodiment. Member 22 has two pins 23 and 24 rigidlyattached. Members 25, 26, 27 and 33 are each identically formedcomponents which are formed to an arc centred upon the assembly shown inFIG. 16.9 and each of members 25, 26,27 and 33 are free to rotate uponpins 23 and 24. To complete the joint two yokes are provided identicalto those shown in FIG. 16.6 one such yoke is located on pins 28 and 29while the other yoke is located on pins 30 and 31. Centering means areprovided as disclosed on the first described joint consisting of members12, 13, 18, 19, 20 and 21 as shown in FIGS. 16.5, 6 and 7. FIG. 16.10 isa depiction of the assembled joint shown while the axis of the inputshaft and output shaft are in line and the view shown is directly alongthe axis of shaft 2 as numbered in FIG. 16.2. Only the ends of the forksof yoke 3 are visible in this view. It will be seen that with operationof the last described joint at any time that the axis of the input shaftand the output shaft are inclined to one another then there is aspherical triangle formed by the intercepted arcs of the trihedralformed by the axis of pins 23, 28 and 31 and a further identicalspherical triangle formed by the intercepted arcs of the trihedralformed by the axis of pins 24, 29 and 30 excepting that twice perrevolution when the axis of pins 28 and 31 are coaxial there ismomentarily no trihedral formed on either side of the joint. It willalso be seen that with operation of the joint pins 28, 29, 30 and 31each describe great circle arcs and a great circle arc exists betweenthe axis of pins 28 and 31 and also between the axis of pins 29 and 30.It will be observed that with operation of the last described jointthere are four constantly changing spherical triangle formed within thejoint in that in addition to the last described spherical trianglesthere are the two spherical triangles associated with the centeringmeans described above.

14. Fourteenth Embodiment

A further modification enable by adhering to spherical geometry ratherthan planar geometry is shown with reference to FIG. 16.11 of FIGS. 16.This further modification provides for a linkage mechanism identical tothat shown in FIG. 16.9 excepting that members 27 and 33 are omitted.With reference to FIG. 16.12 there is also provided two yokes as shownin FIG. 16.6 excepting that one arm on each of the yokes is omitted orshortened, it will be observed that in order to maintain pins 19 and 20on the same side of the joint it is necessary to extend at least one ofthe foreshortened arms so as to locate pin 20 or pin 19 as the case maybe in the required position. With this iteration it will be seen thatoperation is identical to the last described joint excepting that thespherical triangles related to pins 23 and 24 are both right sphericaltriangles formed between the axis of pins 23 and 31 and the point wherethe arc described by pin 31 intercepts the arc of the plane of rotationof pin 23 and the identical triangle is formed on the other side inrelation to pins 24, 30 and the arc of pin 24.

It will be observed that in the last three described joints thecentering means itself is capable of transmitting power through thejoint and in the joints described it does take part of the load. It ispossible therefore to construct a constant velocity joint constructedsolely from the centering means provided by pins 19, 20 together withthe members depicted in FIGS. 16.5 and 16.7.

With reference to FIG. 16.13 shaft 12 is rigidly located to a surface bybearing means 36 and associated mount. Shafts 37 and 38 are also rigidlyfixed in such a manner that while the angle between their axes may beeither fixed or variable their axes always intersect at the centre ofshaft 12 and the axis of the two crankpins 18 and the axis of pins 19and 20 also intersect at the same point.

It will be readily obvious to an ordinary worker that such an assemblymay be incorporated into a stand alone supporting means such as a hollowball joint from which extends tubes so as to locate shafts 37 and 38.

15. Fifteenth Embodiment

With reference to FIGS. 16, a further embodiment is described below.While each of the above described embodiments may be broadly classed asmodified Hooke's joints a quite different embodiment can be describedwhich is more akin to the Rzeppa joint. With reference to FIG. 16.14there is provided a member substantially similar to that depicted inFIG. 16.12 excepting that the spherical plane of the spherical triangledescribed by members 25 is a solid member 36 of at least that size andshape and similarly on the other side of the joint the spherical planedescribed by member 26 is also a solid member of at least that size andshape. (notwithstanding the appearance of the drawing in FIG. 16.14 theassembly is symmetrical). Formed into the surface of each solid 36 and37 is a groove which describes a great circle as would be described bypins 30 and 31 if they were present in this iteration. There is alsoprovided two yokes 38 and 39 as depicted in FIG. 16.15 each such yokehaving an extended and curved arm and each having a groove 40 and 41formed in the inside surface of each of yoke 38 and 39 such that withoperation of the joint the ball rolls in the grooves with sliding orskidding. Assembly of this joint is similar to the foregoingdescriptions where yokes are used excepting that a ball is interposedbetween yoke 39 and solid 36 and also between yoke 38 and solid 37. Inthe last described iteration the third and fourth spherical trianglesformed are formed by the great circle arcs between the axis of pin 23and the centre of the ball and between the point where the path of theball intercepts the plane of rotation of pin 23 and similarly on theother side, the first and second spherical triangles are formed by thecentering means as described elsewhere above.

From the foregoing it will be observed that a potential commoncharacteristic where all of the moving members operate to describespherical geometry paths and constructions of the type referred to inthis specification it is believed possible to construct forms ofsubstantially constant velocity joints where there are no sliding and/orskidding members. It may also possible to reduce all of the componentmembers to members of simple construction whereas in all iterations ofthe prior art relating to constant velocity joints which do not adhereto spherical geometric functions it is submitted that there is bothsliding and/or skidding components and also members of extremely complexconstruction.

16. Sixteenth Embodiment

FIG. 17.1 is a copy of FIG. 16.2 and is a representation of the twohalves of a modified Hooke's joint as is well known and referred to inthe earlier embodiments. With reference to FIG. 17.2 the method of thissixteenth embodiment provides for two yokes 3 and 4 each of which have apin 19 and 20 located on the inside arcuate surface of the said yokes asdisclosed in the earlier embodiments. FIG. 17.3 and FIG. 17.4 representthe members which are unique to the presently described or disclosedcentering means. FIG. 17.3 is a representation of a circular ring likemember having an inside diameter greater than the diameter of the ringmember 5 shown in FIG. 17.1 FIG. 17.4 is a further circular ring likemember having an inside diameter greater than the outside diameter ofthe circular member shown in FIG. 17.3. With reference to FIG. 17.3circular ring like member 21 has two lugs or trunnions 24 and 25diametrically opposed to one another and holes with bearing means 22 and23 to permit or facilitate assembly of ring 21 on axis A5 as shown inFIG. 17.6. With reference to FIG. 17.4 circular ring like member 26 hastwo diametrically opposed holes with bearing means to permit orfacilitate assembly of ring member 26 with ring member 21 where lugs ortrunnions 24 and 25 are located in bearing means 27 and 28 respectively.With further reference to FIG. 17.4 members 29 and 30 are pins havingtheir axis coaxial with a radii of ring member 26 and each of the saidpins being equally angularly disposed from the centre of bearing means27 and 28 respectively. Circular ring like members 21 and 26 areassembled as shown in FIG. 17.5 and further assemble in relation to thejoint as shown in FIG. 17.6. Two arcuate members as depicted in FIG.17.7 are provided with each having an arc or angle between holes 32 and33 being equal to the angle between members 29 and 19 and also betweenmembers 30 and 20 when the axis of shafts 1 and 2 are in line with oneanother so that a first spherical triangle is formed on the first halfof the joint shown in FIG. 17.6 and a second spherical triangle isformed on the second half of the joint shown in. FIG. 17.6 with thefirst spherical triangle being formed by the great circle arcs existingbetween pin 29 and pin 19 and pin 19 and the axis of shaft 1 and theaxis of shaft 1 and pin 29. The second spherical triangle is formed bythe great circle arcs existing between the corresponding points andmembers in the second half of the joint.

It will be observed that the assembly disclosed herein effectivelyperforms the identical function as does the assembly described in thetwelfth embodiment wherein the shaft with the crankpin at either end isutilized to perform the identical task as does ring member 26 and pins29 and 30 as disclosed herein.

The assembly disclosed herein facilitates the use of a member asdepicted in FIG. 17.8. The member depicted in FIG. 17.8 is a shaftmember adapted to connect to the center of the joint as either an inputshaft or output shaft in place of one of the yoke members. So as tofacilitate operation of the centering mechanism as disclosed herein themember shown in FIG. 17.8 has an arcuate slot 36 formed therein so as topermit ring members 21 and 26 to pass through and within the saidarcuate slot there is provided a pin 37 so as to perform the same taskas pin 19 or 20 as the case may be. FIG. 17.9 is a depiction of thelinkage mechanism disclosed in the eleventh embodiment. It will beobserved that the centering means disclosed herein together with themember depicted in FIG. 17.8 is particularly applicable as a suitablecentering means for a constant velocity joint utilizing the linkagemeans depicted in FIG. 17.9. In such an application bearing 22 and 23would be located by pins 38 and 39 respectively.

The present embodiment is a further instance of the centering meanswhich forms a first spherical triangle in a first half of a constantvelocity joint and also forms an identical spherical triangle in asecond half of a constant velocity joint so as to maintain or constrainmembers of the joint on the homokinetic plane of the joint as the saidspherical triangles continuously change but remain identical to oneanother with operation of the joint.

17. Seventeenth Embodiment

This embodiment, with reference to FIGS. 18 is a hybrid of the earlierjoints disclosed together with a truncated instance of the specificinstance of the centering mechanism disclosed in the sixteenthembodiment.

With reference to FIGS. 18, FIG. 18.1 is yoke member 1 with a shaft 2attached and holes 4 and 5 in the yoke member. A pin 3 protruding fromthe inside arcuate surface of the yoke 1. The axis A1 of pin 3intersects the axis A2 of holes 4 and axis A3 of shaft 2. FIG. 18.2 is acircular member 6 having four equally spaced holes 7, 8, 9 and 10 in thesides. FIG. 18.3 is a further circular member 11 having an outsidediameter smaller than the inside diameter of circular member 6. Circularmember 11 has four equally spaced holes 12, 13, 14 and 15 in the sides.

FIG. 18.4 and FIG. 18.5 are a side elevation and plan respectively of a'shaft member 16 having a hole 17 through it and protrusion 18 attached.Two arcuate members 19 and 20 are attached to protrusion 18 one of whichis solely for balance purposes while the other is to provide supportingmeans for pin 21. The axis A5 of pin 21 intersects axis A4 and A:6 whichare the axis of shaft 16 and hole 17 respectively.

FIG. 18.6 depicts part circular members 22 and 23. Member 22 has a pin24 which is assembled into hole 25 and supported by bearing means 26such hat member 22 may rotate on axis A7.

Member 22 has pins 27 and 28 equally spaced from axis A7.

FIG. 18.7 depicts an arcuate member having two holes 30 and 31, two suchmembers are provided.

Assembly of the various component parts is shown in FIG. 18.8, FIG. 18.9and FIG. 18.10 which are a plan view and side elevation section and sideelevation respectively of the assembled joint. One member 29 isassembled on pins 27 and 3 while the second member 29 is assembled onpins 28 and 21.

FIG. 18.11 is a further view of the assembled joint with components notnumbered.

FIG. 18.12 is a representation of the two spherical triangles formed bythe above assembly. The first spherical triangle has the sides formed bythe great circle arcs between members 3, 27 and 24 while the secondspherical triangle is formed by the great circle a members 21, 28 and24. It will be observed that when the axis members 2 and 16 are coaxialthen both of the abovementioned spherical triangles are right sphericaltriangles and that with operation of the joint at any time when axis A4and A3 are not coaxial then the said spherical triangles continuouslychange but remain identical to one another with the result that the pinconnecting means 60 between members 11, 6 and 23 is constrained tocontinuously rotate on the homokinetic plane of the joint.

With reference to FIG. 18.13 which is a representation of a sphere,spherical triangles A,B,C and A,E.D are formed with the relationshipsshown and with the corresponding members of the joint shown in brackets.

As an alternative to the members disclosed and depicted in FIG. 18.4 andFIG. 18.5 member 11 is provided with a series of lands and grooves orspline cut into the inner circular surface and holes 12 and 13 areomitted. In such an embodiment an arm is rigidly fixed to thealternative member 11 so as to locate pin 21 in the same relativeposition as disclosed herein.

18. Eighteenth Embodiment

With reference to FIG. 19.1 this embodiment introduces the doubling ofthe equal spherical triangle centering mechanism disclosed in theearlier embodiments, to become the scissor mechanism employed in thecoupling of the first embodiment.

19. Nineteenth Embodiment

With reference to FIGS. 20, this embodiment has two forms, firstly aconstant velocity joint or coupling for coupling two shafts which havefixed angular axial displacement and secondly a constant velocityuniversal joint or coupling for the coupling of two shafts which havevariable angular axial displacement. In both instances the extended axisof the two shafts intersect at a point and in the second instance theaxis may also be coaxial.

With reference to FIG. 20.1 there is provided a means to rigidly locateat least three pins or trunions equally radially spaced from a centralaxis and equally angularly spaced from one another and such that theextended axis of the said pins or trunnions all intersect at a point.FIG. 20.1 shows one preferred embodiment of such a member and theembodiment shown is on the bottom of part spherical concave profile andon the top of part spherical convex profile and has three equallydimensioned arms radiating from the centre of the member and three holesare provided, one in each arm for the receiving of a pin.

For the purpose of this embodiment as it relates to joints or couplingsfor shafts having a fixed angular displacement there is provided twosuch members as depicted in FIG. 20.1 with the concave inner surface ofthe first such member of a greater radius than the convex outer surfaceof the second such member such difference in radii being greater thanthe radial thickness of the linkage member set out in FIG. 20.2 anddescribed below. FIG. 20.2 depicts a curved or part spherical memberhaving essentially parallel sides and a pin protruding from either endsuch that the extended axis of the said pins intersect at a point whichis also intersected by a radial bisecting the axis of the two pins andperpendicular to the inner or concave surface of the said member. Onesuch pin protrudes from the concave side while the second such pinprotrudes from the convex side. The outer or convex surface having aradius less than the concave side of the first or larger instance of themember depicted in FIG. 1 while the inner or concave surface has aradius greater than the convex surface of the second or smaller instanceof the member depicted in FIG. 20.1.

For the purpose of this embodiment of as it relates to couplings forshafts having a fixed angular displacement there is provided threeinstances of the member depicted in FIG. 20.1 each of identicaldimension and each such member has an angular distance between the axisof the pins at either end equal to the fixed angular displacement of theshafts which it is intended to couple but in no instance can that anglebe greater than the angle of the lesser great circle arc between any twoof the holes in the members depicted in FIG. 20.1 minus the anglebetween the axis of a pin of the curved member depicted in FIG. 20.2 andits nearest adjacent end.

The above described members are assembled as follows.

-   -   1. The pin protruding from the convex side of each of the three        instances of the member depicted in FIG. 2 is rotatably located        into the holes in the concave surface of the larger instance of        the members depicted in FIG. 20.1.    -   2. The pin protruding from the concave side of the member        depicted in FIG. 20.2 is rotatably located in the holes in the        convex surface of the smaller instance of the member depicted in        FIG. 20.1.

The above described members and assembly thereof provide a three layeredassembly where each of the three instances of the members depicted inFIG. 20.2 connect or link between a hole in the larger instance of themember depicted in FIG. 20.1 with a hole in the smaller instance of themember depicted in FIG. 20.1 and where the extended axis of each of thepins protruding from each of the three instances of the member depictedin FIG. 20.2 and the extended axis of each of the holes in bothinstances of the member depicted in FIG. 20.1 intersect at a point. Inaddition with the above assembly the arc between the axis of the pins ofeach one of the three instances of the member depicted in FIG. 2 lies ona great circle arc centred upon the point of intersection of all of thebefore mentioned axis namely the extended axis of each of the threeholes in the larger instance of the member depicted in FIG. 20.1 and theextended axis of the three holes in the smaller instance of the memberdepicted in FIG. 20.1 and the extended axis of each of the pinsprotruding from each of the three instances of the member depicted inFIG. 20.2. In addition the axis of each of the instances of the memberdepicted in FIG. 20.1 also intersect at the same point.

FIG. 20.3 is a schematic, side elevation, sectional, depiction of theabove described assembly without regard to perspective. With respect toFIG. 20.3 member 1 is the larger instance of the member depicted in FIG.20.1, members 2 and 3 are a first and second instance of the memberdepicted in FIG. 20.2, member 6 is the smaller instance of the memberdepicted in FIG. 20.1, members 4. 5, 7 and 8 are the pins protrudingfrom members 2 and 3 as described above and each such pin is located ina hole of either the larger or smaller instance of the member depictedin FIG. 20.1. Axis A1. A3, A4 and A6 are each extended axis of the pins7,4, 8 and 5 respectively and axis A2 and A5 are respectively the axisof members 6 and 1.

The above described assembly provides a constant velocity linkage systemwhereby if axis A2 and A5 are held in fixed relationship to each otherand member 1 is caused to rotate about axis A5 then the linkagesprovided between members 1 and 6 by each of the three instances of themember depicted in FIG. 20.2 two of which are visible in the view shownin FIG. 20.3 will cause member 6 to rotate about axis A2 at an identicalangular velocity to the rotation of member 1 about axis A5 and thereverse is also true in that if member 6 is caused to rotate about axisA2 then the said linkages will cause member I to rotate about axis A5 atan identical angular velocity to member 6.

Using the above described assembly or linkage system is it possible toprovide a constant velocity coupling or joint for two shafts having afixed angular displacement. Where the above described assembly isschematically represented by a block representation as set out in FIG.20.4 attention is drawn to FIG. 20.5 which is a representation of acomplete joint or coupling.

With regard to FIG. 20.5 base 12 is a solid base having a corner 15around which it is required to transmit shaft power from a first shaft10 to a second shaft 11. Shaft 10 is rigidly mounted to base 12 by meansof bearing and mounting means 13 and shaft 11 is similarly rigidlymounted to base 12 by bearing and mounting means 14. Any suitableconnecting means is used to rigidly connect shaft 10 to assembly 9 suchthat it is fixed to member 6 and coaxial with axis A2 as depicted inFIG. 20.3 and similarly any suitable fixing means are used to rigidlyconnect shaft 10 to assembly 9 such that it is fixed to member 1 andcoaxial with axis A5 as depicted in FIG. 20.3. Point B is the point ofintersection of all of the above described axis and also of the axis ofshafts 10 and 11. Such an assembly will transmit power at a constant oruniform angular velocity from shaft 10 to shaft 11.

In order to provide a constant velocity universal joint or couplingcapable of transmitting power between shafts having a variable angularaxial offset there is firstly provided an assembly identical to thatdescribed above and depicted in FIG. 20.3 together with three furtherinstances of the members depicted in FIG. 20.2 and one further instanceof the member depicted in FIG. 20.1 where the further three instances ofthe member depicted in FIG. 20.2 and the further instance of the memberdepicted in FIG. 20.1 have a decreasing radius so as to form a furtherlayer added below or more central to the point B as depicted in FIG.20.3 to the earlier described assembly, although the members decrease inphysical size their angular size is identical to those correspondingmembers in the higher layers so that all axis intersect at a point.

FIG. 20.6 is a representation of an embodiment configured to provide anassembly suitable for inclusion in a joint or coupling where the shaftshave a variable angular relationship to one another. Member 22 is athird instance of the member depicted in FIG. 20.1 and has the sameangular size as the first two instances of the said member namelymembers 1 and 6. Members 16 and 17 are a fourth and fifth instance ofthe member depicted in FIG. 20.2 and they have the same angular size asthe first three instances. It should be noted that the third and sixthinstance of the member depicted in FIG. 20.2 are not visible and notshown in the perspective shown in FIG. 20.6. Shaft 23 is rigidlyconnected to the centre of the concave surface of member 22 and shaft 24is rigidly connected to the convex surface of member 1 such that in theposition of the assembly as depicted in FIG. 20.6 shafts 23 and 24 arecoaxial with one another and also coaxial with the axis of members 1 and22. All axes converge on point B.

In order for the last described assembly to function as a constantvelocity universal joint it is necessary to provide a mounting orcoupling which provides for angular movement of the axis of shafts 23and 24 while concurrently constraining the axis of shafts 23 and 24 suchthat at any time when the axis of the said shafts are not coaxial theyintersect at a point. Where the assembly depicted in FIG. 20.6 asdescribed above is schematically represented by a block representationsas depicted in FIG. 20.7 attention is first drawn FIG. 20.8 which is arepresentation depicting the important relationships between the shaftsand the assembly disclosed above. During operation of the joint of thisembodiment it is important that point B as shown in FIG. 20.6 alwaysfalls on the axis of shaft 23 and it is important that a point on theaxis of shaft 24 always falls on a spherical plane centred upon point B.If constructed with sufficient strength and tolerance the assemblydepicted in FIG. 20.6 will maintain the required relationships oralternatively constraining means may be provided to maintain the saidrelationships, one example of such a constraining mechanism is depictedin FIG. 20.9.

With respect to FIG. 9 yoke 25 has a bearing means 26 adapted to receiveshaft 24 such that shaft 24 may rotate within bearing means 26. Bearingmeans 27 is adapted to receive shaft 23 such that shaft 23 may rotatewithin bearing means 27 but is held rigidly such that point B as 10depicted in FIG. 20.6 and FIG. 20.8 is always located at theintersection of the axis A7 and A8. Axis A7 is the axis for bearingmeans 27 within housing 28, axis A8 in turn is the axis for housing 28.

It will be seen that with an assembly such as that disclosed herein anddepicted in FIG. 20.6 and constrained so that point B as depicted inFIG. 20.6 is the point of axis of all the above mentioned axes, there isprovided a constant velocity universal joint without any load bearingsliding surfaces as distinct from rotating surfaces and which has alloperating members operating to transfer or transmit the torque from afirst shaft to a second shaft being of part spherical construction andoperating within a spherical system.

There is claimed a joint having the characteristics inherent in theconstruction disclosed and a joint based upon spherical geometry and ajoint having the construction first described and depicted in FIG. 20.3and a joint having the construction second described and depicted inFIG. 20.6 and there is claimed a mounting means as described and set outin FIG. 20.5 and also FIG. 20.9.

20. Twentieth Embodiment

With reference to FIGS. 21, this embodiment provides for two instancesof the assembly depicted in FIG. 21.3 which is a spherical four barlinkage with the extended axes of each of the four axis A1, A2, A3 andA4 in the linkage extending to a single point and where the arcs betweeneach axis form great circle arcs.

A mounting means is provided in the centre of the double yoke member 5such that the two instances of the assembly depicted in FIG. 21.3 areheld within double yoke member 5 in relationship to each other asdepicted in FIG. 21.4. In FIG. 21.4 points P1 and P2 represent thecentre of cruciform members 1 and 2 respectively, C1 and C2 are greatcircles of spheres centred upon points P1 and P2 respectively.

A pin (not shown) extends from shaft members 3 and 4 such that the axisof each such pin extends radial from point P1 and P2 respectively whenassembled and forms the axis for axis A3 in each instance of theassembly depicted in FIG. 21.3.

It will be observed that with such an assembly if means are provided tocause both instances of the assembly depicted in FIG. 21.3 to moveuniformly with operation of the joint then the angle between shaft 1 anddouble yoke member 5 will remain the same as the angle between shaft 4and double yoke member 5 and the necessary requirements for a constantvelocity joint of the double Cardan type will have been satisfied.

One method of ensuring that the two instance of the assembly depicted inFIG. 21.3 move uniformly is to rigidly connect the first instance ofmember 6 with the second instance of member 6 and similarly rigidlyconnect the two instances of member 7.

One method of rigidly connecting each instance of member 6 to each otheris to provide a single member as shown in FIG. 21.5 where pins 10 and 11provide the axis for each of the two instances of axis A2 and hole 12 isaxis A1.

It will be observed without further illustration that the two instancesof member 7 may also be constructed as a single component as in FIG.21.5.

21. Twenty-First Embodiment

With reference to FIGS. 22, a further embodiment is described forconstraining the mechanism of the seventeenth embodiment so that thespherical triangles formed by that mechanism remain identical to oneanother with operation of the joint.

FIG. 22.1 hereof is a further depiction of the mechanism depicted inFIG. 18.12 thereof. FIG. 22.2 hereof is a depiction of the mechanismdisclosed in the eighteenth embodiment. FIG. 22.3 hereof is an explodedview of a constant velocity joint according to the disclosures of theseventeenth and eighteenth embodiments. FIGS. 22.4, 5 and 6 areassembled views of that joint with the spherical assembly numbered 7 inFIG. 22.3 being the spherical linkage disclosed in substance in theeighteenth embodiment.

With reference to FIG. 22.1 hereof it will be observed that arm or bar 1is free to pivot about axis A1 and arm or bar 2 is free to pivot aboutaxis A2 such that angles 4 and 5 which are the angles between bar 1 andbar 3 and between bar 2 and bar 3 respectively may differ from oneanother. The present disclosure is to provide a means whereby angles 4and 5 are continuously essentially identical to one another with theresult that the two spherical triangles formed by the mechanism remainidentical to one another.

According to the present embodiment, with reference to FIG. 22.7 hereofthere is provided a mechanism as disclosed in FIG. 1 hereof with theaddition of a gear wheel 6 interposed between arm 1 and arm 2. Arm 1 andarm 2 are each provided with gear teeth to mesh with gear wheel 3. Withsuch a mechanism it will be observed that angles 4 and 5 will alwaysremain substantially identical to one another with the result that thespherical triangles formed by the mechanism also remain substantiallyidentical to one another.

According to the present embodiment therefore there is disclosed acentering mechanism as depicted in FIG. 22.7 and there is provided aconstant velocity joint as depicted in FIGS. 22.3, 4, 5 and 6 whereinthe centering mechanism 7 is replaced with the mechanism disclosed inFIG. 22.7 hereof.

SUMMARY Summary of Embodiments First Embodiment

A constant velocity coupling wherein the axes of all rotational elementsintersect at the intersection of the input and output shaft axes. Thecoupling is provided with a control yoke and control mechanism whereinthe control yoke defines an axis of rotation bisecting the supplementaryangle between the input shaft axis and output shaft axis of thecoupling.

The control mechanism is in the form of a double scissor assembly whereall linkages have axes radial to the intersection point of the input andoutput shaft axes, the pivoting centers of the control linkageseffectively lying at the vertices of equal spherical triangles.

Second Embodiment

A constant velocity coupling wherein all elements are identical to thoseof the first embodiment except that the control mechanism consists of ageared mechanism where two linkage arms provided with gear segments meshwith a central gear, this assembly controlling the axis of the controlyoke to lie on the bisector of the supplementary angle between the inputand output shaft axes.

Third Embodiment

A constant velocity coupling wherein either the scissor mechanism of thefirst embodiment, or the geared mechanism of the second embodimentcontrolling the axis of the control yoke to lie on the bisector of thesupplementary angle between the input and output shaft axes but wherethe inner and outer yokes are modified from a full circular form to apartial segment form.

Fourth Embodiment

A constant velocity coupling where the rotational elements supportingthe ends of the input and output shafts are separated by a connectingtube and where the connecting tube supports a control mechanism suchthat the tube axis is constrained to lie on the bisector of thesupplementary angle between the input and output shafts.

Fifth Embodiment

A constant velocity coupling in which the angle between the input andoutput shafts may be varied from time to time by a control mechanism,the control mechanism further constraining the orientation of a controlyoke such that its axis of rotation lies on the bisector of thesupplementary angle between the input and output shafts. The couplingincorporates a swash plate variable hydraulic displacement device.

Additional Embodiments

In one form an embodiment provides for a constant velocity coupling in afirst form in which a control mechanism may be tailored to a particularfixed angle between the axes of the input shaft and the output shaftusing a limited assembly of control elements. The control elements arebased on spherical geometrical forms.

In a second form, an extended assembly of similar control elements areadapted to provide a control mechanism for a constant velocity couplingin which the angle between input and output shafts is variable.

In a further embodiment a constant velocity coupling is provided havinga control mechanism of the form described in the first preferredembodiment. The initial form (as disclosed in PR5731) comprised one halfof the scissor mechanism of the first embodiment with the modificationto the double scissor system in PR5992.

In a further embodiment, the conditions for a constant velocity couplingare realized through a variety of linkages to constrain the alignment ofthe axis of rotation of a control yoke such that the axis bisects thesupplementary angle between the axes of the input and output shafts ofthe coupling. The control linkages are formed as elements based on arcsof spherical triangles.

In a further embodiment a linkage mechanism is disclosed which is anovel realization of the principles of an inner and outer yoke system orgimbal system such as commonly used in double Cardan joints. It is inthe form of the yoke mechanism as utilized in the fourth preferredembodiment.

Yet a further embodiment discloses a centering mechanism for a constantvelocity coupling comprising a system of intermeshing pinion gears andlevers to control the angular relationship between the two halves of thecoupling.

With particular reference to the first embodiment described withreference to FIGS. 1 to 4 it will be noted that a significant number ofthe characteristics referred to in the introductory portion of thedetailed description with reference to FIG. 23 are exhibited by thisembodiment including:

-   -   (a) The control yoke in conjunction with the scissor mechanism        and forming the control mechanism for the gimbal assembly        comprising the inner and outer yoke operates entirely        symmetrically about the supplementary angle bisector 308        (designated C in FIG. 4);    -   (b) All axes of the control mechanism pass through the coupling        centre 307 (also termed geometric centre);    -   (c) The otherwise substantially unconstrained linkage between        the input and output shafts provided by the gimbal mechanism in        the form of the inner yoke and outer yoke is constrained by the        control mechanism in the form of the control yoke, in this        instance so that axis YY (referred to in FIG. 1) lies on the        homokinetic plane.

The above describes only some embodiments of the present invention andmodifications, obvious to those skilled in the art, can be made theretowithout departing from the scope and spirit of the present invention.

1-87. (canceled)
 88. A constant velocity coupling wherein the conditionsfor equal instantaneous transfer of angular velocities between an inputand an output shaft are maintained by a control mechanism, said couplingcomprising, (a) an input shaft rotation axis (b) an output shaftrotation axis (c) a control mechanism, said control mechanism adapted toconstrain at least portions of said coupling so as to achieve a constantvelocity characteristic; said control mechanism based on sphericalgeometry with respect to a geometric centre defined as the intersectionof said input shaft rotation axis and said output shaft rotation axis.89. The constant velocity coupling of claim 88 said control mechanismfurther comprising means for centering; said means for centeringincorporating rotational joints defined with respect to sphericaltriangle structures so as to constrain at least portions of the constantvelocity coupling on a homokinetic plane defined with respect to thepoint of intersection of the input axis with the output shaft rotationaxis of said constant velocity coupling.
 90. The constant velocitycoupling of claim 89 wherein all rotation axes intersect at a commonpoint, said point defined as the geometric center of said coupling. 91.The constant velocity coupling of claim 90 wherein the elements of saidcontrol mechanism are constrained to move as arcs on great circles ofspheres centered at said geometric center of said coupling.
 92. Theconstant velocity coupling of claim 91 wherein an axis of rotation ofsaid control mechanism lies on a bisector of a supplementary angle ofsaid input and output axes.
 93. The coupling of claim 92 wherein saidinput rotation axis terminates in a boss having an axis of rotation atright angles to the axis of said input shaft, the intersection of saidaxes coinciding with said geometric center of said coupling.
 94. Thecoupling of claim 93 wherein said boss is adapted to rotate about anaxis of a first inner yoke pair of journals of an inner yoke.
 95. Thecoupling of claim 94 wherein said inner yoke is provided with a secondinner yoke pair of journals, said first and second pairs of inner yokejournals defining rotation axes at right angles to each other andintersecting at a point coinciding with said geometric center of saidcoupling.
 96. The coupling of claim 95 wherein each of the journals ofsaid first pair of inner yoke journals of said inner yoke is equidistantfrom said geometric center of said coupling.
 97. The coupling of claim96 wherein each of the journals of said second pair of inner yokejournals of said inner yoke is equidistant from said geometric center ofsaid coupling.
 98. The coupling of claim 97 wherein the axis of saidsecond pair of inner yoke journals is adapted to rotate about the axisof a first pair of outer yoke journals of an outer yoke.
 99. Thecoupling of claim 98 wherein said outer yoke is provided with a secondpair of outer yoke journals, said first and second pairs of outer yokejournals defining rotation axes which intersect at said geometric centerof said coupling.
 100. The coupling of claim 99 wherein each of thejournals of said first pair of outer yoke journals is equidistant fromsaid geometric center of said coupling.
 101. The coupling of claim 100wherein each of the journals of said second pair of outer yoke journalsis equidistant from said geometric center of said coupling.
 102. Thecoupling of claim 101 wherein a control yoke is provided of generallyU-shaped form having control yoke journals at its outer ends of thecontrol yoke.
 103. The coupling of claim 102 wherein said control yokejournals are adapted to rotate about the axis of said first outer yokepair of journals of said outer yoke.
 104. The coupling of claim 103wherein each of the journals of said control yoke journals isequidistant from said geometric center of said coupling.
 105. Thecoupling of claim 104 wherein said outer yoke is provided with a secondpair of outer yoke journals, said first and second pairs of outer yokejournals defining rotation axes which intersect at said geometric centerof said coupling.
 106. The coupling of claim 105 wherein each of thejournals of said first pair of outer yoke journals of said outer yoke isequidistant from said geometric center of said coupling.
 107. Thecoupling of claim 106 wherein each of the journals of said second pairof outer yoke journals of said outer yoke is equidistant from saidgeometric center of said coupling.